Method of removing naphthalene from solvent naphtha



Patented Apr. 14, 1931 PATENT OFFICE FRANK IE. MARQUARD, F CLAIRTON, PENNSYLVANIA METHOD OF REMOVING NAPHTHALENE FROM SOLVENT NAPHTHA No Drawing. Application filed July 1,

This invention relates to the purification and recovery of distillates containing resins or resinitying constituents, and more particularly coal tar distillates comprising solvent naphtha containing useful resinous constituents and naphthalene.

An ob'ect of the invention is to provide a process y which naphthalene may be removed trom the solvent naphtha without polymerizing the resins or resinifying constituents.

Another object of the invention is to provide a solvent naphtha distillate substantially tree from naphthalene and containing a 1;; quantity of resinifying constituents.

Vith these and other objects in view, the invention comprises the process and product described in the following specification and claims.

In the following description the invention is illustrated as applied to a coal tar distillate or fraction known in the trade as No. 2 crude heavy solvent naphtha. This fraction is obtained from the benzol light oil fraction of coal tar by distilling ott first a fraction having a distilling point of 81 0., and consisting principally of benzol, then a fraction at 110.2 0., containing a toluol, and then a fraction ranging from 137 to 140 G., containing xylol,

and then a fraction ranging from about 160 (1, to 195 (1, which forms the No. 2 crude heavy solvent. This fraction also contains the cumeron and indine resins or constituents forming these resins u on polymerization.

In the distillation o? the coal tar to form the No. 2 crude heavy solvent naphtha, a quantity of naphthalene is carried over with the vapors, the quantity ranging from 1 to 8% of naphthalene. This naphthalene cannot be separated and removed by means of sulphuric acid without, at the same time, polymerizing the resins and thus removing them from the fraction.

In accordance with thepresentinventionthe No. 2 crude heavy solvent naphtha containing the resins and naphthalene impurity is mixed with an absorbent petroleum oil known gen erally as wash oil and having a distillation range of from about 230 to 330 C., and containingl' only a small amount of hydrocarlwns 1929. Serial No. 375,337.

that are easily broken down or decomposed by heat. This type of wash oil is commonly and generally used for absorbing benzol out of the gases obtained from the destructive distillation of coal.

The Wash oil and crude heavy solvent naphtha are preferably mixed in approximately equal proportions. The mixture is then subjected to distillation and the solvent naphtha is distilled of? from the wash oil, which retains the naphthalene. The resins or resinitying constituents of the fraction pass over with the distillate. By selectinga mineral oil or wash oil materially above the boiling point range of the solvent naphtha being treated, Us the distillation may be readily carried out without a substantial loss of the required solvent naphtha. At'ter distilling oil the sol vent naphtha and the resins or r'esinifying products, the Wash oil may be used in the usual manner for absorbing a fresh quantity of benzol from the coal distillation gases. The purified distillate is substantially free from naphthalene and contains a large quantity of resins or resinifying products ranging from 30 to 00 per cent. These resins may then be polyn'icrized and removed, leaving a solvent naphtha suitable for paints, etc.

Although the invention has been described for the removal of naphthalene from N o. 2 crude heavy solvent naphtha, it will be understood that it may be applied generally to distillates containing naphthalene as an impurity and also containing resins or resinifying substances which it is desired to obtain free from naphthalene without polymerizing.

What I claim is:

1. A process of separating naphthalene from a heavy crude solvent naphtha containng resin constituents and naphthalene which comprises adding a quantity of a hydrocan bon oil having a boiling point materially higher than the boiling point of the heavy crude solvent naphtha being processed to said heavy crude solvent naphtha, and then distilling oil? the solvent naphtha and resin constituents.

2. A process of separating naphthalene from a heavy crude solvent naphtha containing resin constituerfts and naphthalene which 101) comprises mixing said solvent naphtha being processed With substantially equal proportions of a hydrocarbon oil having a boiling point materially higher than the boiling point of said solvent naphtha being processed, and then distilling off the solvent naphtha and resin constituents. v

3. A process of separating naphthalene from a crude solvent naphtha cpnta iningresin constituents and naphthalene which comprises mixing said solvent naphtha being processed with a quantity of a hydrocarbon oil having a boiling point materially higher than the boiling point of said solvent-naphtha being processed, and thendistilling the solvent naphtha and resin constituents fromithe naphthalene and hydrocarbon oil.

4. A process of separatingnaphthalene from a crude solvent naphtha recovered from the destructive distillation of coal and containing resin constituents and naphthalene which comprises mixing said solvent naphtha being processed with aqnantity of mineral oil having a boiling point materially higher than the boiling point of said solvent naphtha being processed, and then subject-- ing said mixture to distillation to distil off the solvent naphtha and resin constituents from the mineral oil and naphthalene. In testimony whereof, I have hereunto set my hand.

FRANK F. BEARQUARD. 

